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c++ convert infix to prefix

Vishvajeet Singh Nayal 21BCE3732 answered on August 21, 2022 Popularity 8/10 Helpfulness 5/10

answer c++ convert infix to prefix

c++ convert infix to prefix

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#include<iostream>
#include<cstdlib>
#include<cstring>
#include<algorithm>
using namespace std;

class stackk
{    
    public :
    int top;
    char arr[15];

    stackk()
    {
        top =-1;
        for(int i=0; i<=15; i++)
        {
            arr[i]=0;
        }
    }
      
     bool isOperator(char c)
    {
       if(c == '^' || c == '/' || c =='*' || c=='+' || c=='-')
       {
        return true;
       }
       else
       {
        return false;
       }
    }
     
      int precedence(char c)
    {
        if(c == '^')
        {
            return 3;
        }
        else if(c =='*' || c=='/')
        {
            return 2;
        }

        else if(c =='+' || c=='-') 
        {
            return 1;
        }
        else 
        {
            return -1;
        }
    }
      
       bool empty()
    {
        if(top == -1)
        {
            return true;
        }

        else 
        {
            return false;
        }
    }

     bool full()
     {
        if(arr[top]==15)
        {
            return true;
        }

        else
        {
           return false;
        }
     }

      char pop()
      {
        if(empty())
        {
            cout<<" cant pop stack is already empty"<<endl;
            return -1;
        }
      else
      {
        char pop_value = arr[top];
        arr[top] = 0;
        top--;
        return pop_value;
      }
      }
    
    void push(char val)
    {
        if(full())
         {
            cout<<" cant push stack is already full "<<endl;
        }
        else
        {
        top++;
        arr[top] = val;
        }
    }
    
   char topf()
    {
        return arr[top];
    }

    string infixtoPrefix(char arr , string in , int n)
    {
        string prefix;
reverse(in.begin() , in.end());
for(int i=0; i<n; i++)
{
if(in[i]=='(')
{
    in[i]==')';
}
else if(in[i]==')')
{
    in[i]=='(';
}
}

for(int i =0; i<n; i++)
{
    if((in[i] >= 'a' && in[i]<='z') || (in[i] >='A' && in[i]<='Z' ))
    {
      prefix += in[i];  
    }
    else if( in[i]=='(')
    {
        push(in[i]);
    }
    else if(in[i]==')')
    {
        while((topf() != '(') && (!empty()))
        { 
            prefix += topf();
            pop();

        }

        if(topf() == '(')
        {
            pop();
        }
    }

    else if(isOperator(in[i]))
    {
        if(empty())
        {
            push(in[i]);
        }
         else
          {
            if(precedence(in[i])>precedence(topf()))
         {
            push(in[i]);
         }

         else if ((precedence(in[i]) == precedence(topf())) 
         &&  ( in[i]=='^'))
         {
            while(( precedence(in[i]) == precedence(topf()))
            &&(in[i] == '^'))
            {
             prefix += topf();
             pop();
            }
            push(in[i]);
         }

         else if(precedence(in[i]) == precedence(topf()))
         {
            push(in[i]);
         }
         else
         {
           while((!empty()) && (precedence(in[i]) < precedence(topf())))
           {
            prefix += topf();
            pop();
           }
          push(in[i]);
         }

        }
    }
}

while(!empty())
{
    prefix += topf();
    pop();
}

reverse(prefix.begin(), prefix.end());
return prefix;
    }
};

int main()
{
 stackk S;
 string input;
   cout<<" enter the infix axpression : "<<endl;
   cin>>input;
   int n  = input.length();
   cout<<" prefix expression is : " << S.infixtoPrefix(S.arr[15] ,  input ,  n);
return 0;
}

Popularity 8/10 Helpfulness 5/10 Language cpp

Source: Grepper

Tags: c++ prefix

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Contributed on Aug 21 2022

Vishvajeet Singh Nayal 21BCE3732

0 Answers Avg Quality 2/10

c++ convert infix to prefix

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